Providing services with different Quality of Service (QoS) requirements to users is an active study area for the future-generation communication system. Especially, studies are being actively conducted on supporting high-speed services by ensuring mobility and QoS to Broadband Wireless Access (BWA) communication systems such as Wireless Local Area Network (WLAN) and Wireless Metropolitan Area Network (WMAN). A major example of the BWA communication systems is Institute of Electrical and Electronics Engineers (IEEE) 802.16e.
To increase data transmission capacity and improve QoS, the future-generation communication system controls downlink and uplink transmit power such that a Base Station (BS) or a Mobile Station (MS) transmits a signal with a minimum strength enough to enable the other party to have an acceptable Signal-to-Interference and Noise Ratio (SINR) for data reception. With the power control, the BS transmits a signal with a high transmit power to an MS with a low SINR, thereby rendering data communication between them to be stable and suppressing the QoS degradation of the MS.
The power control scheme controls the transmit power of a transmitter so that a receiver can keep its SINR at an acceptable level. Particularly, an Orthogonal Frequency Division Multiplexing or Orthogonal Frequency Division Multiple Access (OFDM/OFDMA) communication system maximizes transmit power within a range that prevents mutual interference between neighbor base stations, for example, within a range where data exchanged between neighbor base stations and mobile stations serviced by the neighbor base stations do not interfere with one another, thus improving reception quality (i.e., QoS).
Meanwhile, the communication system needs to differentiate the transmit power of an MS at the center of the cell area of a serving BS and thus in a good channel status from an MS at a cell boundary area and thus in a poor channel status, in power control. For example, if the MS at the cell boundary transmits a signal with a high transmit power, the signal interferes with a neighbor BS. Hence, the MS is controlled to transmit a signal with a minimum transmit power that meets an SINR requirement for data transmission and reception in a receiver. If the MS at the center of the cell transmits a signal with a high transmit power, the signal does not interfere much with the neighbor BS. Hence, the MS is allowed to transmit a signal with a high transmit power in order to improve the QoS of transmitted and received signals. Accordingly, there exists a need for a technique for controlling the transmit power of data in a communication system.